package org.fuyd.util;

/**
 * 该类主要用于取一个字符串的SHA1值
 * 
 * @author 永德
 *
 */
public class EncryptySHA1 {
  // 将字节数组转换为十六进制字符串
  private static String byteArrayToHexString(byte[] bytearray) {
    String strDigest = "";
    for (int i = 0; i < bytearray.length; i++) {
      strDigest += byteToHexString(bytearray[i]);
    }
    return strDigest;
  }
  // 将字节转换为十六进制字符串
  private static String byteToHexString(byte ib) {
    char[] Digit = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
    char[] ob = new char[2];
    ob[0] = Digit[(ib >>> 4) & 0X0F];
    ob[1] = Digit[ib & 0X0F];
    String s = new String(ob);
    return s;
  }
  public static void main(String[] args) {
    String data = "abcd";
    System.out.println(data);
    String digest = new EncryptySHA1().getDigestOfString(data.getBytes());
    System.out.println(digest);
    String s = new EncryptySHA1().getSHA1CodeOfString(data);
    System.out.println(s);
  }

  private final int[] abcde = {0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476, 0xc3d2e1f0};

  // 摘要数据存储数组
  private int[] digestInt = new int[5];

  // 计算过程中的临时数据存储数组
  private int[] tmpData = new int[80];

  // 格式化输入字节数组格式
  private byte[] byteArrayFormatData(byte[] bytedata) {
    // 补0数量
    int zeros = 0;
    // 补位后总位数
    int size = 0;
    // 原始数据长度
    int n = bytedata.length;
    // 模64后的剩余位数
    int m = n % 64;
    // 计算添加0的个数以及添加10后的总长度
    if (m < 56) {
      zeros = 55 - m;
      size = n - m + 64;
    } else if (m == 56) {
      zeros = 63;
      size = n + 8 + 64;
    } else {
      zeros = 63 - m + 56;
      size = (n + 64) - m + 64;
    }
    // 补位后生成的新数组内容
    byte[] newbyte = new byte[size];
    // 复制数组的前面部分
    System.arraycopy(bytedata, 0, newbyte, 0, n);
    // 获得数组Append数据元素的位置
    int l = n;
    // 补1操作
    newbyte[l++] = (byte) 0x80;
    // 补0操作
    for (int i = 0; i < zeros; i++) {
      newbyte[l++] = (byte) 0x00;
    }
    // 计算数据长度，补数据长度位共8字节，长整型
    long N = (long) n * 8;
    byte h8 = (byte) (N & 0xFF);
    byte h7 = (byte) ((N >> 8) & 0xFF);
    byte h6 = (byte) ((N >> 16) & 0xFF);
    byte h5 = (byte) ((N >> 24) & 0xFF);
    byte h4 = (byte) ((N >> 32) & 0xFF);
    byte h3 = (byte) ((N >> 40) & 0xFF);
    byte h2 = (byte) ((N >> 48) & 0xFF);
    byte h1 = (byte) (N >> 56);
    newbyte[l++] = h1;
    newbyte[l++] = h2;
    newbyte[l++] = h3;
    newbyte[l++] = h4;
    newbyte[l++] = h5;
    newbyte[l++] = h6;
    newbyte[l++] = h7;
    newbyte[l++] = h8;
    return newbyte;
  }

  // 4字节数组转换为整数
  private int byteArrayToInt(byte[] bytedata, int i) {
    return ((bytedata[i] & 0xff) << 24) | ((bytedata[i + 1] & 0xff) << 16)
        | ((bytedata[i + 2] & 0xff) << 8) | (bytedata[i + 3] & 0xff);
  }

  // 单元摘要计算函数
  private void encrypt() {
    for (int i = 16; i <= 79; i++) {
      tmpData[i] = f4(tmpData[i - 3] ^ tmpData[i - 8] ^ tmpData[i - 14] ^ tmpData[i - 16], 1);
    }
    int[] tmpabcde = new int[5];
    for (int i1 = 0; i1 < tmpabcde.length; i1++) {
      tmpabcde[i1] = digestInt[i1];
    }
    for (int j = 0; j <= 19; j++) {
      int tmp =
          f4(tmpabcde[0], 5) + f1(tmpabcde[1], tmpabcde[2], tmpabcde[3]) + tmpabcde[4] + tmpData[j]
              + 0x5a827999;
      tmpabcde[4] = tmpabcde[3];
      tmpabcde[3] = tmpabcde[2];
      tmpabcde[2] = f4(tmpabcde[1], 30);
      tmpabcde[1] = tmpabcde[0];
      tmpabcde[0] = tmp;
    }
    for (int k = 20; k <= 39; k++) {
      int tmp =
          f4(tmpabcde[0], 5) + f2(tmpabcde[1], tmpabcde[2], tmpabcde[3]) + tmpabcde[4] + tmpData[k]
              + 0x6ed9eba1;
      tmpabcde[4] = tmpabcde[3];
      tmpabcde[3] = tmpabcde[2];
      tmpabcde[2] = f4(tmpabcde[1], 30);
      tmpabcde[1] = tmpabcde[0];
      tmpabcde[0] = tmp;
    }
    for (int l = 40; l <= 59; l++) {
      int tmp =
          f4(tmpabcde[0], 5) + f3(tmpabcde[1], tmpabcde[2], tmpabcde[3]) + tmpabcde[4] + tmpData[l]
              + 0x8f1bbcdc;
      tmpabcde[4] = tmpabcde[3];
      tmpabcde[3] = tmpabcde[2];
      tmpabcde[2] = f4(tmpabcde[1], 30);
      tmpabcde[1] = tmpabcde[0];
      tmpabcde[0] = tmp;
    }
    for (int m = 60; m <= 79; m++) {
      int tmp =
          f4(tmpabcde[0], 5) + f2(tmpabcde[1], tmpabcde[2], tmpabcde[3]) + tmpabcde[4] + tmpData[m]
              + 0xca62c1d6;
      tmpabcde[4] = tmpabcde[3];
      tmpabcde[3] = tmpabcde[2];
      tmpabcde[2] = f4(tmpabcde[1], 30);
      tmpabcde[1] = tmpabcde[0];
      tmpabcde[0] = tmp;
    }
    for (int i2 = 0; i2 < tmpabcde.length; i2++) {
      digestInt[i2] = digestInt[i2] + tmpabcde[i2];
    }
    for (int n = 0; n < tmpData.length; n++) {
      tmpData[n] = 0;
    }
  }

  private int f1(int x, int y, int z) {
    return (x & y) | (~x & z);
  }

  private int f2(int x, int y, int z) {
    return x ^ y ^ z;
  }

  private int f3(int x, int y, int z) {
    return (x & y) | (x & z) | (y & z);
  }

  private int f4(int x, int y) {
    return (x << y) | x >>> (32 - y);
  }

  // 计算sha-1摘要，返回相应的字节数组
  public byte[] getDigestOfBytes(byte[] byteData) {
    process_input_bytes(byteData);
    byte[] digest = new byte[20];
    for (int i = 0; i < digestInt.length; i++) {
      intToByteArray(digestInt[i], digest, i * 4);
    }
    return digest;
  }

  // 计算sha-1摘要，返回相应的十六进制字符串
  public String getDigestOfString(byte[] byteData) {
    return byteArrayToHexString(getDigestOfBytes(byteData));
  }

  // 计算字符串的哈希摘要，返回相应的十六进制字符串
  public String getSHA1CodeOfString(String string) {
    return getDigestOfString(string.getBytes());
  }

  // 整数转换为4字节数组
  private void intToByteArray(int intValue, byte[] byteData, int i) {
    byteData[i] = (byte) (intValue >>> 24);
    byteData[i + 1] = (byte) (intValue >>> 16);
    byteData[i + 2] = (byte) (intValue >>> 8);
    byteData[i + 3] = (byte) intValue;
  }

  // 计算sha-1摘要
  private int process_input_bytes(byte[] bytedata) {
    // 初试化常量
    System.arraycopy(abcde, 0, digestInt, 0, abcde.length);
    // 格式化输入字节数组，补10及长度数据
    byte[] newbyte = byteArrayFormatData(bytedata);
    // 获取数据摘要计算的数据单元个数
    int MCount = newbyte.length / 64;
    // 循环对每个数据单元进行摘要计算
    for (int pos = 0; pos < MCount; pos++) {
      // 将每个单元的数据转换成16个整型数据，并保存到tmpData的前16个数组元素中
      for (int j = 0; j < 16; j++) {
        tmpData[j] = byteArrayToInt(newbyte, (pos * 64) + (j * 4));
      }
      // 摘要计算函数
      encrypt();
    }
    return 20;
  }

}
